Configure interfaces and pbr for RHEL and its derivatives  
Supported iterface types for network-scripts:
- ethernet (default)
- loopback

For RHEL8 use:

    network:
      network_manager:
        iface:
          - conn_name: ens256
            ip4:
              - "100.127.2.2/29"
          - conn_name: dummy0
            type: dummy
            ip4:
              - "18.12.3.1/32"
            routes4:
              - 0.0.0.0/0 100.127.2.6 table=200
              - 100.127.2.0/29 100.127.2.2 table=200
            routing_rules4:
              - priority 5 from 18.12.3.1 table 200
    
For RHEL7 use: 

    network:
      network_scripts:
        iface:
          - name: ens256
            ip:
              - ipaddr: "100.127.2.2"
                prefix: "29"
          - name: lo
            type: loopback
            ip:
              - ipaddr: "18.12.3.1"
                prefix: "32"
            route:
              - default table 200 via 100.127.2.6
              - 100.127.2.0/29 table 200 via 100.127.2.2
            rule:
              - from 18.12.3.1 table 200
        pbr:
          table:
            - number: 200
              name: "prod"